/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 * 
 *
 *Redistribution and use in source and binary forms, with or without 
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the 
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For 
 * further information contact the Community Grids Lab at 
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and 
 * wherever such third-party acknowledgments normally appear.
 * 
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering, 
 * shall not be used to endorse or promote products derived from this software 
 * without prior written permission from Indiana University.  For written 
 * permission, please contact the Advanced Research and Technology Institute 
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering, 
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 * 
 *
 * Indiana University provides no reassurances that the source code provided 
 * does not infringe the patent or any other intellectual property rights of 
 * any other entity.  Indiana University disclaims any liability to any 
 * recipient for claims brought by any other entity based on infringement of 
 * intellectual property rights or otherwise.  
 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO 
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF 
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS. 
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS", 
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.  
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR 
 *ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION 
 *GENERATED USING SOFTWARE.
 */
package cgl.narada.matching.tagvalue;

import cgl.narada.util.ByteUtilities;

/**
 * Predicate.java
 * @author Shrideep Pallickara 
 * $Revision$
 * $Date$
 */

public class Predicate implements MatchingDebugFlags {
   
  private String subscription;
  private int destinations;
  private String brokerDestination=null;
  private boolean includesBrokerInfo = false;
  
  /** A Predicate is comprised of both the subscription as well as the 
      destination of the unit/super-unit that has expressed an interest in it.
      @param subscription The subscription is tag=value, tag=value pairs 
      @param destinations The hierarchial destinations associated with this
      predicate */
  public Predicate(String subscription, int destinations) {
    this.subscription = subscription;
    this.destinations = destinations;
  }
  

  public Predicate(String subscription, String brokerDestination,
		   int destinations) {
    this.subscription = subscription;
    this.brokerDestination = brokerDestination;
    this.destinations = destinations;
    includesBrokerInfo = true;
  }

  /** This method serves to unmarshall a predicate stream received over the
      link. The corresponding marshalling method for the predicate is contained
      within the getBytes() method.
      @param predicateBytes The marshalled stream of predicate bytes that are
      received over a link.
  */
  public Predicate(byte[] predicateBytes) {
    int offset =0;
    byte[] lengthBytes = new byte[4];
    System.arraycopy(predicateBytes, offset, 
		     lengthBytes, 0, 4);
    offset+=4;
    int subscriptionLength = ByteUtilities.getInt(lengthBytes);
    //int subscriptionLength = predicateBytes[offset++];
    
    
    subscription = new String(predicateBytes, offset, subscriptionLength);
    offset+=subscriptionLength;

    byte[] destBytes = new byte[4];
    System.arraycopy(predicateBytes, offset, destBytes, 0, 4);
    destinations = ByteUtilities.getInt(destBytes);
    
    offset+=4;
    
    if (offset != predicateBytes.length) {
      byte[] brokerDestLengthBytes = new byte[4];
      System.arraycopy(predicateBytes, offset,
		       brokerDestLengthBytes, 0, 4);
      offset+=4;
      int brokerDestLength = ByteUtilities.getInt(brokerDestLengthBytes);
      brokerDestination = new String(predicateBytes, offset,
				     brokerDestLength);
      includesBrokerInfo = true;
    }

    if (Predicate_Debug) {
      System.out.println("Subscription = " + subscription + 
			 " Destination = " + destinations );
    }
  }

  /** This method returns the subscription associated with the predicate.
      @return The subscription.
  */
  public String getSubscription() {
    return subscription;
  }

  /** This method returns the destinations assocaited with the subscription.
      @return The destinations.
  */
  public int getDestination() {
    return destinations;
  }

  public String getBrokerDestination() {
    return brokerDestination;
  }

  
  public String getPredicateId() {
    /** The ID that is generated should be a unique one and should be 
	reproducible anywhere. The method would return a null if such a 
	unique ID generation isn't possible */ 
    if (includesBrokerInfo) {
      String predicateId = brokerDestination + ":" + destinations +
	"[" + subscription.hashCode() + "]";
      return predicateId;
    }
    return null;
  }
  
  /**
     Compares two objects for equality. Returns a boolean that indicates
     whether this object is equivalent to the specified object. This method
     is used when an object is stored in a hashtable.
     @param _predicate the Object to compare with
     @return true if these Objects are equal; false otherwise.
     @see java.util.Hashtable
  */
  public boolean equals(Predicate _predicate) {
    if (subscription.equals(_predicate.getSubscription()) ) {
      return true;
    }
    else 
      return false;
  }
  
  /**
     Generates a hash code for the receiver. This method is supported 
     primarily for hash tables, such as those provided in java.util.
     If two objects are equal (equals(Object) returns true) they must have the 
     same hash code
     @return an integer hash code for the receiver 
  */
  public int hashCode() {
    return subscription.hashCode();
  }
  
  /** This method returns the predicate as a stream of bytes, the unmarshalling
      counterpart to this marshalling scheme is contained within one of 
      the Predicate constructors 
      @return The byte stream representation of the predicate 
  */
  public byte[] getBytes() {
    byte[] subscriptionBytes = subscription.getBytes();
    byte[] destBytes         = ByteUtilities.getBytes(destinations);    
    byte[] brokerDestinationBytes=null;
    
    int predicateLength=  4 /* length of the subscription */ +
      subscriptionBytes.length +   destBytes.length;

    if (includesBrokerInfo) {
      brokerDestinationBytes = brokerDestination.getBytes();
      predicateLength += (4 /*length of brokerDestination*/ +
			  brokerDestinationBytes.length);
    }
    
    byte[] predicateBytes = new byte[predicateLength]; 
    
    int offset=0;
    /** The length of the subscription */
    System.arraycopy(ByteUtilities.getBytes(subscriptionBytes.length), 0,
		     predicateBytes, offset, 4);
    offset+= 4;
    //predicateBytes[offset++] = (byte) subscriptionBytes.length;

    System.arraycopy(subscriptionBytes, 0, 
		     predicateBytes, offset, subscriptionBytes.length);
    offset+= subscriptionBytes.length;
    
    System.arraycopy(destBytes, 0,
		     predicateBytes, offset, destBytes.length);
    offset+=4;

    /** If the predicate includes the broker info, marshall this info too */
    if (includesBrokerInfo) {
      System.arraycopy(ByteUtilities.getBytes(brokerDestinationBytes.length), 
		       0, predicateBytes, offset, 4);
      offset+=4;
      System.arraycopy(brokerDestinationBytes, 0, 
		       predicateBytes, offset, brokerDestinationBytes.length);
      offset+= brokerDestinationBytes.length;
    }
    
    return predicateBytes;
  }

  /** Provides a string representation of the predicate instance. 
      @return Predicate as a String object.
  */
  public String toString() {
    String info = "Subscription Predicate = " + subscription + 
      " Destination = " + destinations;
    return info;
  }
  
  
  public static void main(String[] args) {
    String sub1 = "A=a, B=b, C=c, D=d";
    Predicate predicate = new Predicate(sub1, 123);
    /** This is a test for the unmarshalling operation that we are doing */
    new Predicate(predicate.getBytes());

  }

}
